javascript regex for region code

Question

I have a regex problem with validation for a region code. My region code could be only one digit but it also could be a digits separated by '-'

for Example my region code could be one of the following:
6
6-66
77-7

As you can see I must have at least one digit or digits separated by '-' and if they are separated there should be a digits after the '-' sign (does not matter how many). So 6- must not be validated as legal region code. I try 2 hours to solve this, but I couldn't, so please help me! Thank you!

Answer 1

/\d+(-\d+)?$/

This will match 6, 6-66,77-7, but not6-`

Answer 2

If what you are looking for is the whole string:

/^\d+(?:-\d+)?$/

or something like that:

if (parseInt(yourstring.split(/-/)[0])>=eval(yourstring)) alert('true');
else alert('false');

But it is more complicated :) and less efficient! And if the condition is false you code will crash!

Answer 3

var data = ['6', '6-66', '77-7', '6-'];

var len = data.length;

for(var i=0; i<len; ++i) {
  var current = data[i];
  var result = data[i].match(/^(\d+|\d+[-]\d+)$/);
  if(result != null) {
    console.log(current);
  }
}

--output:--
6
6-66
77-7

Answer 4

For a quick answer you can try following:

 /^([0-9])|([0-9]\-[0-9][0-9])|([0-9][0-9]\-[0-9])$/

or in case your engine support perl-styled character classes:

 /^(\d)|(\d\-\d\d)|(\d\d\-\d)$/

here what it does:

1. between / and / resides as string defining a regular expression

2. \d stands for one digit it coudl also be writen as [0-9]

3. () defines a sub-expression, so (\d) matches your first one-digit, (\d-\d\d) second three digits style, and last (\d\d-\d) third variant of three-digit region code

4. | goes as "OR" like (A)|(B)|(C), so by combining previous three we will get:

   /(\d)|(\d-\d\d)|(\d\d-\d)/

5. Finally ^ means start of string, and $ - end of string.

also there is so called BRE mode (in which you have to add "\" symbol before each parentheses), but I think it is not the case. However if you would have some free time, please consider any quick tutorial like this one.